Investigating Amorphous Composition Mix Design Performance and Properties of Fly Ash-Based Geopolymer

Abstract

Identifying viable replacement for Ordinary Portland Cement (OPC) is part of the effort to limit CO2 emission during its production. Fly ash-based geopolymer composites have emerged as a sustainable and promising replacement product with proven comparable binding properties, coupled with superior characteristic in some area, when compared to OPC. However, fly ash being a by-product of coal combustion, remains unfavourable in industry application due to its deferring composition dependent on the type of coal feedstock, resulted in inconsistent mechanical and chemical properties produced. In order to overcome this shortcoming, a unified method to evaluate fly ash at the amorphous composition level is required. This study aims to tackle this challenge by establishing a framework to effectively identify relationship among the fly ash amorphous content and identifying an optimum proportion of alkaline activator in order to optimise its full potential in geopolymer concrete or mortar production. This is achieved by utilising XRF and Q-XRD analyses on geopolymer specimen’s amorphous compositions and evaluate their respective compressive strength through laboratory testing. A number of testing variants are carried out including curing regime, alkaline activator concentrations, presence of mechanical activation and deferring water content are investigated.